More than half (53%) of the 1,145 UK parents surveyed said bringing up teenagers was harder than caring for a newborn baby.

Nearly a quarter of parents claimed 13-year-olds were the most difficult, the Netmums research showed.

But by the time children reach 17, parents say their relationship with them dramatically improves, with just one in 50 families saying they still have issues.

Teens' refusal to help at home was the biggest flashpoint for parents, with 55% of families rowing over it.

Just under two in five (39%) argued over teenagers' laziness and a third fought over teens' lack of interest in their school work.

The difficulties of being a teenager in the 21st century were also laid bare, with three in five parents admitting their child suffered from "anxiety".

Almost half of these teens (49%) worried about "being cool and fitting in", the Netmums research showed.

A further 47% worried about their popularity on social networks while 38% fretted about their weight.

But only 42% were concerned about passing exams or going to college and just a over quarter (27%) of teenagers were anxious about getting a job in the future, according to the research.

Two thirds of parents revealed their teen suffered serious mood swings with 4% seriously concerned their teen could be depressed.

One in seven parents also said their teen was "very body conscious" and was trying to change their body shape through diet or exercise. And one in eight mums felt they were passing on their own body anxieties to their children.

Parents were also concerned about their child's anger levels with a third (33%) saying their child slammed doors and shouted at them at least twice a week.

One in seven parents (14%) also suspected their child was sexually active - with 43% claiming their child had lost their virginity under the age of consent.

Over half of parents (51%) had to talk to their child's school over issues with their teen.

But 83% said they were "coping well" with teens' moods and anxiety.

And four in five parents also said there was "far more pressure" on teenagers now than when they were growing up, so they were trying to be more understanding.

Netmums founder Siobhan Freegard said: "As the century turns teenage in 2013, we wanted to see how Britain's families with teenagers are coping.

"It's certainly true that children are growing up faster than ever, as while 16 used to be the flashpoint as kids came of age, increasing pressure on youngsters to fit in, look good and be cool means parents now say 13 is the toughest time.

"But having been teens themselves, parents are better at understanding the pressures than teenagers realise, with four in five recognising their children are under unprecedented pressure.

"So, as teens always say, the world is certainly 'not fair', their parents are doing all they can to help them cope with it and navigate it."